1. Field of the Invention
The present invention is directed to a shock wave source of the type suitable for treatment of calculi in the body of a patient, and in particular to such a shock wave source having a tube closed at one end by a flexible cover which can be pressed against the patient and closed at the other end by an electrically conductive membrane which is repelled by a flat coil supplied with high voltage pulses.
2. Description of the Prior Art
Shock wave sources are known which generate focused shock waves which can be directed at a calculus to be disintegrated in the body of a patient, for example a kidney stone. The calculus is shattered to such a degree that it can be eliminated naturally. The generation of the shock wave is undertaken by discharging a high voltage capacitor through a flat coil which may, for example, be in the form of a helical winding. An electrically conductive membrane is disposed adjacent to, but spaced from, the coil, and is repelled upon the occurrence of the high voltage pulse in the coil. The sudden movement of the membrane generates a shock wave in the volume between the membrane and the flexible covering. This shock wave is directed through a shock wave conducting medium in volume at the calculus by means of an acoustic lens in the shock wave tube.
Shock wave sources of this type are known wherein both one end of the coil and the membrane lie at ground potential. If a high voltage of, for example 20 kV is applied to the flat coil for generating a shock wave, the full high-voltage will be between a point of the flat coil and the membrane. The layer of insulation between the flat coil and the membrane must therefore have dimensions capable of insulating the entire high-voltage. Nonetheless, arcing is not always successfully avoided. A destruction of the membrane occurs as a result of such arcing.